1. Field of the Invention
The invention relates to a flat-shaped preparation, consisting of a sheet-like, film-like or wafer-like administration form whose structure comprises two layers, which layers are provided with a coding in the form of characters, graphic symbols or patterns for identifying the substances which can be released therefrom during use. This preparation is especially suited for administering substances affecting flavour or odour and/or care or curative substances. The invention also indicates processes by means of which the above-mentioned administration forms can be provided with codings.
2. Description of the Related Art
Manufacturers of pharmaceutical products are increasingly obliged to identify not only the primary packaging, but also the product itself. This especially applies to medicaments in an administration form aimed at controlling the release of active substance.
According to the prior art, in the case of medicaments in the form of coated tablets, capsules or sheet-like or film-like products such identification or coding is usually accomplished in an additional operation following the actual manufacture, namely by printing or punching of special identification marks or patterns.
In addition to the outlay necessitated by this, with correspondingly increased production costs, the originality and proofness against forgery are not particularly good, especially in the case of printing, as it is relatively easy to apply, or remove, such markings afterwards. Printing has the additional disadvantage of serving exclusively for identification while having no further function, for example in terms of the modification of release or of an increase in the possible loading, and it is therefore relatively expensive.
For tablets, methods of identification are known where during the manufacture relief-like signs or patterns are produced. According to the processes described in U.S. Pat. No. 5,516,530, respectively WO 95/09608, the tablet material is cast as a dispersion into a mould wherein the signs or patterns have been pre-formed. After solidification of the mass under action of pressure, freezing or freeze-drying, a tablet is obtained which has the pre-determined relief-like embossing. It will be readily appreciated that this method is unsuited for providing identification marks on sheet-like, film-like or wafer-like administration forms.
DE-OS 196 46 836 A1 describes a single-layered administration form of the type last-named which is provided with an identification marking or coding. This is provided in the form of thickness gradients, i.e. depressions and elevations, in the flat preparations. In this way a visual effect is produced which is comparable to watermarks. To achieve these patterns, the preparation mass is coated onto an appropriately structured support, or the patterns are applied afterwards, under action of pressure. The described type of identification does, however, have the disadvantage of not being particularly clearly visible. The main reason for this is that it is only monochromatic and can be recognized only because of small light/dark contrasts at its contours. An additional factor is that the thickness gradients making these watermark-like patterns visible are only within the μm range. In the case of the thin administration forms mentioned, it is not possible to further increase the thickness gradients in order to improve perceptibility.
A further disadvantage, not to be underestimated, of the administration form disclosed in DE-OS 196 46 836 A1 is that by applying the patterns in the form of depressions, the average layer thickness—and thus also the maximum possible loading with active substances—is overall reduced. For administration forms which anyway cannot be highly loaded owing to their dimensions, e.g. film-like administration forms, this disadvantage is particularly significant.